The Khewra salt mine (also known as Mayo Salt mine named in the honor of Lord Mayo, who visited the mine as Viceroy of India) is a part of salt range originated about 800 million years ago after a shallow sea evaporated and following geological movements stretched it to about 300 kilometers.

The Khewra Salt Mine is one of the largest of the world and is part of the Salt Range Formation, which contains the thickest (approximately 5000 feet) seams of rock salt in the world. This precambrian formation is divided into three members, all well exposed on both sides of the Khewra Gorge. Also visible, the (early) Cambrian Khewra Sandstone presents honeycomb weathering, cross-bedding and intera-formational folds.

The Salt Range is one of the most important geological regions in Pakistan. It is easily accessible and displays a wide variety of geological features and paleontological remains. It has, therefore, been rightly called a field museum of geology and paleontology.